Motion-picture apparatus.



G. F. JENKINS.

MOTION PICTURE APPARATUS.

APPLIGATION FILED MAY 1o, 1911.

Patentd Dec. l?, 1912.

of the expensive film while also causing unpleasant results 1n thepictures on the screen SHINGTON, DISTRICT OF COLUMBIA.

CHARLES FRANCIS JENKINS, 0F WA 4i union.

MOTXGN-PICTURE APPARATUS.

Specification of Letters Eatent.

Patented Dec. 1?, 1912.

Application led May 10, 1911. Serial No. 626,396.

To all whom it may concern:

Be it known that I, CHARLES; FRANCIS JENKiNs, a citizen of the UnitedStates, residing at lVashin'gton, in the District of Columbia, haveinvented certain new and useful 'improvements in Motion-PictureApparatus, of which the following is a specifi.d cation, reference beinghad therein to the accompanying drawing.

This invention 'relates to devices for avoiding serious tension uponmoving picture film as it is rewound after leaving the projectingapparatus. Practically it is found necessary to wind the films which areoften many hundreds of feet in length, but as the film is delivered at aconstant rate by the projecting d evices and as the roll upon the drumnecessarily increases in diameter the film rlrum necessarily tends totake 'up the film more and more rapidly, the rate with long filmsincreasing many fold. Obviously this must be compensated or the use ofthe method is impossible. A common expedient is to drive the windingdrum by devices allowing slip of the. parts whenever a low tension uponthe film is exceeded. But as the roll increases. this slip-causingtension acts through anincreasing lever arm always equal to the radiusof the growing roll, and hence the pull necessary to cause slipping atone stage of the winding is many times that required at another time,whence it follows that during a part of the winding period, it beingimpracticable to vary the force needed to produce slipping, there isundesirable tension upon the film. Film is at best short lived, andsince tension upon it is principally exerted in pulling the film edges,at two perforations, against the faces of two narrow sprocket drumteeth, such tension as has been described seriously 'shortens'the lifeas soon as any. wear or injury results.

To provide a simple and convenient means for avoiding` the difficulty isthe object of this invention, and this object is attained by providingdevices which automatically wind the film at precisely the rate of itsdelivery no matter what the diameter of the roll.

ln the accompanying drawings, Figure 1 is a side elevation of a portionof a projecting apparatus involving my novel devices.' Fig. 2 a detailview of a portion of the roll driving devices.

In these figures,

A represents a suitable a similar gear H support, B the casing of aportion of common projecting apparatus provided with a lens C and adriving crank D, and C the casing for the film winding drum D mountedupon a shaft E. Upon this shaft is also fixed a large disk F. One of theshafts of 'the film feeding apparatus within the casing B, for examplethe shaft X of the usual lower sprocket drum, projects from the casingand bears a bevel gear H which engages extending downward alongside thedisk, parallel thereto and at a short distance therefrom. The shaft ismounted in any suitable bearings, as J, J. Upon the central portion ofthis shaft is splined a small pref. erably rubber faced wheel or rollerK the edge of which presses firmly against the disk and the hub of whichbears, in an annular groove, a loose but nonerotating ring L to which ispivoted one end of a link M. The other end of this link is pivoted tothe free end of a rigid arm N fixed to a rock shaft O mounted in thecasing or in a support therein. This shaft bears a second rigid arm I inthe plane of the film roll and having at its free end a roller P, torest upon the periphery of the latter against which it is held bygravity alone, usually.

The film strip Q, passes out of the casing B, around suitable rollers R,R, and to the film drum, upon which the roller I at first rests whilethe point of contact of the wheel K upon the disk lies in line with asurface elementof the drum. The proportion of the parts is such that thewheel K rotates the disk and drum shaft just fast enough to take up thefilm delivered by the projecting apparatus. As the film winds upon thedrum, increasing its diameter and the length of film wound at each turn,the roller I is pushed away from the drulns axis, rocking the shaft andswinging the other arm, thus pushing the wheel upward on its shaft whereit travels in a larger circle on the disk and thus moves the drumthrough a smaller angular distance for each of its own rotations. Therate of rotation of the drum is thus in inverse proportion to thecircun'lference of the roll and, whatever the diameter' of the i flier,the film is wound as fast as it is delivi red and without lbeinginjuriously pulled against the sprocket teeth of the film feedingdevices within the casing B. In other words, the devices secure aslight, practii` liy constant, ined uniform tension upon a slender shaftl upon the film coming from the projecting devices.

What I claim is:

l. The combinuiion 'with a projecting nm-A ehine und a film boxalongside the Saineyof a Iilni drum mounted in the box, a, friction diskniounied on the drinn shaft, a Shaft in geared connection with seidnia-chine 'and proif'ided 'r'.f'il'li a drum-driving friction roller.impinging on said disk and arranged o elide' on' the shalt Withoutfrotating thereon, and Lwo rigidly connected pivored mn'is.,

one normally pressingto-ward the periphery Iof the drum sind the otherconnected ily e link to said roller to lSlide the seine on irs shaft.

2. The eoinbinalion with u projecting mi chine having im externalrot-ating gear, of a film box, a ilin drum mounted in the loo'Xj afriction dislon the drinn sli-ufr., e roel;- shafty immllel io die drumsimil, an arm projecting from the roclsha't and having n terminal rollernormally resting on lilie druin, a second erin projecting' from therockslmfl, a link pivoially connected to rile .free end of the leiterarm, simil; parallel 'lo a diameter of the diel and provided with apinion e1 j ig said gear, i friction roller sliding' on lie slmft,rotating herewith, in f fonlacl; Willi Smid disk, and revolulilyconnected 'lo (he ifree end of said link, substantially as Sei,ilforlli..

ln teei'imoirr whereof? I aliX my signature in presence el' lireWitnesses CHARLES FR ANGS JENKLNC; Witnecsee:

JAMES L. CRAWFORD, R..- CRAIG GREENE.

